CN112086703A - Resource treatment method for carbon residue of retired battery - Google Patents

Abstract

The invention relates to a resource treatment method of retired battery carbon slag, which comprises the steps of crushing and drying retired battery carbon slag to be treated to obtain fine carbon slag; uniformly mixing the fine carbon slag and the villiaumite to obtain a mixture; then preserving the heat of the mixture for 0.5-4h under the conditions of protective atmosphere and 400 ℃ of 100-; then, the obtained slag is leached out with water or an acidic aqueous solution, then, solid-liquid separation is carried out, and the solid phase is washed with water to obtain leachate and graphite. The method has the advantages of simple process, capability of obtaining the ultra-pure graphite, low roasting temperature, low energy consumption, high treatment efficiency, low environmental pollution, high resource utilization rate, good cycle performance and industrial application prospect.

Description

A resource treatment method for decommissioned battery carbon residue

technical field

The invention relates to a recycling treatment method of decommissioned battery carbon residue, belonging to the technical field of harmless and comprehensive utilization of industrial hazardous waste resources.

Background technique

In recent years, with the global support for the new energy industry, the global battery market demand has grown at an alarming rate. Among them, consumer batteries represented by 3C products and power batteries represented by new energy vehicles have developed the most rapidly. With the continuous expansion of the market size of new energy vehicles and the demand for energy storage batteries, lithium-ion batteries will also increase year by year, and the number of waste lithium-ion batteries after decommissioning will also increase rapidly. Processing and recycling will inevitably lead to a great waste of resources and serious environmental pollution. At present, the recovery technology for decommissioned batteries mainly focuses on the extraction of valuable metal elements in the positive and negative electrode mixture by wet leaching process. During this process, a graphite slag is produced and mixed with some unreacted positive electrode residues. Due to the complex composition of carbon residues, there is currently no effective recovery and treatment method. Generally, it can only be disposed of by accumulation or landfill, which wastes resources and also brings environmental pollution. In response to the industry problem of carbon residue treatment and recovery from decommissioned batteries, industry experts, scholars and front-line production personnel have conducted various explorations and researches.

Li Songxian and Tian Zhongliang studied the recycled carbon from waste lithium iron phosphate batteries. The recycled carbon was regenerated into graphite negative electrode materials by gas-phase oxidation and glucose pyrolysis carbon coating. After 3 h of oxidation in the atmosphere, the irreversible capacity of the carbon material was reduced from 186 mAhg ^-1 before modification to 61.1 mAhg ^-1 in the first cycle, and the Coulomb efficiency of the first cycle was increased from 64.4 % to 86.9 %. Using glucose as the carbon source, the gas-phase modified carbon was coated by the liquid-phase impregnation method. At a current density of 1C (372 mAg ^-1 ), the reversible capacity of the composite after 270 cycles increased from 308.8 mAhg ^-1 before modification. increased to 424.7 mAhg ^-1 , the capacity retention rate increased from 78.0 % to 97.8 %, the cycle stability at high current density was significantly improved, and the high-rate charge-discharge performance was also significantly improved, but the impurities in the carbon slag could not be effectively removed ( Li Songxian. Recycling carbon modification and electrochemical performance of waste lithium iron phosphate batteries [D]. Central South University, 2020).

Chinese invention patent specification CN105552468A discloses a method for recycling graphite negative electrode materials of waste lithium ion batteries. The negative electrode sheets separated from lithium ion batteries are sequentially pretreated by soaking in alkali solution, soaking in acid solution and rinsing in deionized water, and then in Pre-baking, pulverizing, and sieving in an air atmosphere of 300-500 ℃ to obtain a negative electrode active material, and then mixing the obtained negative electrode active material with oxalate wet ball milling, and then treating it at a high temperature of 450-800 ℃ in an inert atmosphere. After cooling, pulverizing and sieving, the battery grade graphite negative electrode material is obtained.

Chinese invention patent specification CN103618120B discloses a method for separating and recycling graphite and copper sheets in waste and old lithium-ion battery negative electrode materials. The waste and old negative electrode materials are soaked in dilute acid and then sieved, and the material under the sieve is a soaking solution containing rough graphite products. Hydrogen peroxide is added to the soaking solution for oxidation, filtration, washing and drying to obtain a preliminarily purified graphite product, which is then subjected to a two-step high temperature treatment to obtain high-carbon graphite.

Chinese invention patent specification CN110835682A discloses a method for synergistic processing of positive and negative active materials of waste lithium ion batteries. The mixture of positive active materials and negative active materials obtained by crushing and separating waste lithium ion batteries is added with an appropriate amount of concentrated sulfuric acid. The solidified clinker is obtained by reaction and aging, and then the obtained solidified clinker is leached with water or dilute acid, and the leaching slurry is separated by sedimentation to obtain a leaching solution containing useful metal elements such as cobalt, lithium, nickel, and titanium, and the leaching residue is centrifuged. Graphite and residues realize synergistic strengthening of positive and negative active materials in spent lithium-ion batteries.

Chinese invention patent specification CN107964593A discloses a method for recovering lithium in scrap lithium battery slag by chlorination roasting and evaporation. The pulverized lithium slag is uniformly mixed with a certain amount of metal chloride, and then the mixed lithium slag and metal chloride are mixed in The molar ratio is 1:1-1:2 and the roasting temperature is 800 ℃ ~ 1200 ℃ under high temperature conditions, so that the lithium in the lithium slag is transferred into the gas phase removal system in the form of lithium chloride, which solves the problem of pyrometallurgical treatment of scrap lithium It is difficult to recover lithium from batteries, but new impurity elements are introduced in the processing process, making it difficult to recover high-quality graphite.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for recycling carbon residues from decommissioned batteries, so as to solve the problem that it is difficult to obtain high-purity graphite in the prior art.

The technical scheme adopted in the present invention is as follows:

A method for recycling carbon residue from decommissioned batteries, wherein the carbon residue from decommissioned batteries is mainly composed of C, Si, Ni, Co, and Mn; the method includes the following steps:

S1. Crushing and drying the carbon slag of the decommissioned battery to be treated to obtain fine carbon slag;

S2, uniformly mixing the fine carbon residue obtained in S1 with the fluoride salt to obtain a mixture; optionally, mixing is performed by an impregnation method or a mechanical mixing method, preferably a mechanical mixing method;

Wherein, the fluoride salt is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, aluminum fluoride, and ammonium bifluoride;

S3. The mixture obtained in S2 is kept in a protective atmosphere at 100-400°C for 0.5-4h to obtain slag and flue gas;

S4, carry out leaching treatment to the slag obtained in S3 in water or an acidic aqueous solution, then separate the solid and liquid, and wash the solid phase to obtain leaching solution and graphite;

Wherein, the purity of the graphite is not less than 99.99%.

Further, in S1, the particle size of the fine carbon residue is less than 150 μm (-100 mesh).

Further, in S2, the fine carbon residue and the fluoride salt are uniformly mixed in a mass ratio of 1:0.1-3 to obtain a mixture, preferably, the fine carbon residue and the fluoride salt are uniformly mixed in a mass ratio of 1:0.5-1.5 .

Preferably, in S2, the fluoride salt is ammonium fluoride. The use of ammonium fluoride can not only meet the phase transformation requirements of impurity elements in the carbon residue, but also the unreacted ammonium fluoride can be acidic in the subsequent solution leaching stage, which is beneficial to lithium fluoride, cobalt fluoride and nickel fluoride in the slag. , the dissolution and separation of manganese fluoride, in addition, under this condition, the aluminum in the slag will be converted into ammonium hexafluoroaluminate, which is easily soluble in water and acid. Therefore, in the case of using ammonium fluoride, the leaching stage Water can be used directly, and C and Al can be effectively separated, which is beneficial to reduce the processing cost.

Further, in S3, the mixture is kept at 150-300° C. in a protective atmosphere for 2-4 hours to obtain slag and flue gas.

Further, in S4, the acidic aqueous solution contains one or more of HCl, HNO ₃ , HF, and H ₂ SO ₄ .

Optionally, the acidic aqueous solution is one or more of hydrochloric acid, nitric acid, hydrofluoric acid, and sulfuric acid.

Further, the acid concentration in the acidic aqueous solution is 1-22 mol/L, further 4-18 mol/L.

Further, in S4, during the leaching treatment, the solid-liquid mass ratio is 1:5-30, preferably 1:10-20; optionally, the leaching temperature is 20-100°C, preferably 40-80°C, and the leaching time 1-4h, preferably 2-3h.

Further, the flue gas obtained by S3 is passed into the leaching solution obtained by S4, and the pH value of the leaching solution is controlled to be 6-10, further 7-9; then add a precipitating agent to the leaching solution, at 30-100 ℃ (preferably 40 -60°C) for 0.5-3h (preferably 1-2h), to obtain waste liquid and metal precipitates, and further, the metal precipitates include Li, Ni, Co, Mn precipitates. In this way, the valuable metals can be enriched, which facilitates the subsequent further recovery and processing of the valuable metals.

Further, the precipitating agent is one or more of ammonium carbonate, ammonium oxalate, oxalic acid and carbonic acid, preferably ammonium carbonate. Further, the added amount of the precipitant is 1-2 times, preferably 1.1-1.4 times, the total molar amount of lithium, nickel, cobalt and manganese in the leaching solution.

Further, the pH value of the waste liquid is adjusted to 3-7, preferably 3-5, followed by cooling and crystallization, centrifugal separation and drying in sequence to obtain fluoride salt. Optionally, the drying is airflow drying. The residual liquid after cooling and crystallization of the waste liquid can be returned to S4 for recycling for leaching.

Further, by adding acid to the waste liquid, adjust its pH value; the acid is at least one of sulfuric acid, hydrofluoric acid, and hydrochloric acid, preferably hydrofluoric acid.

Further, the decommissioned battery is one or more of a lithium cobalt oxide battery, a lithium nickel oxide battery, a lithium manganate battery, and a lithium iron phosphate battery.

Further, the protective atmosphere is at least one of nitrogen, helium, and argon, preferably nitrogen.

Further, in the decommissioned battery carbon residue, the fixed carbon content is 80-90 wt %, the volatile content is 5-10 wt %, and the ash content is 2-8 wt %. Among them, in the ash, the main element content (wt%): Si 10-14, Ni 25-30, O 15-20, Mn 6-10, Co 4-8, Al 4-8, Na 2-7, Fe 2 -6, P 1-6, Zr 1-5, Cu 1-4.

Compared with the prior art, the present invention has the following beneficial effects:

1. By mixing decommissioned battery carbon slag with fluorine salt and then calcining at low temperature, phase reconstruction and rapid transfer of non-carbon elements such as lithium, nickel, cobalt, manganese, Si, and Al can be realized, which can not only effectively remove aluminosilicate It can also convert valuable metals into soluble metal salts, the leaching toxicity of the product can be ignored, and the recycling and harmlessness of hazardous waste products can be realized;

2. By adopting the low temperature roasting and leaching process, the production cost of the enterprise is greatly reduced, the reaction time is shortened, and the impurity removal efficiency is improved.

3. The purity of the graphite obtained by the method of the present invention is as high as 99.99% or more, which can fully meet the requirements for the purity and particle size of the new energy graphite anode material, and can also recover valuable materials such as lithium, nickel, cobalt, and manganese in the carbon residue at the same time. Metal elements realize the efficient recovery and recycling of materials.

4. The process of the invention is simple, the roasting temperature is low, the energy consumption is low, the treatment efficiency is high, the environmental pollution is small, the resource utilization rate is high, the cycle performance is good, and the industrial application prospect is provided.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Fig. 2 is the XRD pattern of the graphite powder obtained in Example 2 of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the embodiments. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

Example 1

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, of which the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn8.63, Co 6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH ₄ F at a mass ratio of 1:0.5, then place the mixture in a corundum crucible, in a muffle furnace in an argon atmosphere at 200°C After 4 hours of heat preservation, and after cooling, the slag was leached with water bath stirring. The leaching temperature was 60°C, the leaching time was 1 hour, and the liquid-solid ratio was 15:1. The water-soaked residue is washed with water until neutral, filtered, and the filter residue is dried, and tested according to the graphite chemical analysis method (GB/T-2008) to obtain ultra-pure graphite powder with a purity of 99.990%.

After the leaching solution was controlled to pH 9 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.2 to the solution was added, and after leaching for 2 hours at a leaching temperature of 60 °C, washing, filtration, and drying were performed to obtain a cobalt-nickel-manganese mixed product, lithium The recovery rates of cobalt, nickel and manganese are as high as 95%, 98%, 99% and 89% respectively. After adding HF and controlling the pH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled to obtain fluoride salts. The supernatant is recycled for the wet leaching process.

Example 2

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn 8.63, Co6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH ₄ F at a mass ratio of 1:1, then place the mixture in a corundum crucible, and place the mixture in a muffle furnace at 250 ° C in an argon atmosphere. Incubate for 4h under conditions, and after cooling, the obtained slag is leached with water bath stirring, leaching temperature: 60°C, leaching time 1h, liquid-solid ratio 15:1. The leaching residue was washed with water until neutral, filtered, and the filter residue was dried, and tested according to the method for chemical analysis of graphite (GB/T-2008) to obtain ultrapure graphite powder with a purity of 99.992%. The XRD pattern of the obtained graphite powder is shown in Figure 2.

After the leaching solution was controlled to pH 9 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.1 to the solution was added as a precipitant, and after leaching for 1 hour at a leaching temperature of 50 °C, washing, filtration, and drying were performed to obtain cobalt, nickel, and manganese. Mixed products, the recovery rates of lithium, cobalt, nickel, and manganese are as high as 94%, 97%, 98%, and 90% respectively. After adding HF to control the PH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled. The fluoride salt is obtained and the supernatant is recycled for the wet leaching process.

Example 3

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn 8.63, Co6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH4F at a mass ratio of 1:0.7, then place the mixture in a corundum crucible, and roast it in a muffle furnace at 200°C for 3h in an argon atmosphere. , after cooling, the obtained slag was leached with water bath stirring, leaching temperature: 70°C, leaching time 2h, liquid-solid ratio 20:1. The water-soaked residue is washed with water until neutral, filtered, and the filter residue is dried, and tested according to the graphite chemical analysis method (GB/T-2008) to obtain ultra-pure graphite powder with a purity of 99.996%.

After the leaching solution was controlled to pH 9 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.2 to the solution was added as a precipitant, and after leaching for 1 hour at a leaching temperature of 60 °C, washed, filtered, and dried to obtain cobalt, nickel, and manganese. Mixed products, the recovery rates of lithium, cobalt, nickel, and manganese are as high as 93%, 97%, 99%, and 85%, respectively. After adding HF to control the PH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled. The fluoride salt is obtained and the supernatant is recycled for the wet leaching process.

Example 4

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn 8.63, Co6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH ₄ F at a mass ratio of 1:0.7, then place the mixture in a corundum crucible and keep it at 300°C in a muffle furnace in an argon atmosphere 4h, after cooling, the obtained slag was leached with water bath stirring, leaching temperature: 70°C, leaching time 3h, liquid-solid ratio 20:1. The water-soaked residue is washed with water until neutral, filtered, and the filter residue is dried, and tested according to the graphite chemical analysis method (GB/T-2008) to obtain ultra-pure graphite powder with a purity of 99.991%.

After the leaching solution was controlled to pH 9 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.4 to the solution was added as a precipitant, and after leaching at a leaching temperature of 60°C for 3 hours, washed, filtered and dried to obtain cobalt, nickel and manganese. Mixed products, the recovery rates of lithium, cobalt, nickel, and manganese are as high as 97%, 99%, 99%, and 92%, respectively. After adding HF to control the PH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled. The fluoride salt is obtained and the supernatant is recycled for the wet leaching process.

Example 5

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn 8.63, Co6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH4F at a mass ratio of 1:1, then place the mixture in a corundum crucible, and keep it in a muffle furnace at 200 °C for 4 hours in an argon atmosphere. After cooling, acid impurity removal was carried out on the obtained slag in sulfuric acid solution. The leaching temperature of sulfuric acid acid leaching was 60°C, leaching time was 1h, and liquid-solid ratio was 15:1. The acid leaching residue was washed with water until neutral, filtered, and the filter residue was dried, and tested according to the method for chemical analysis of graphite (GB/T-2008) to obtain ultrapure graphite powder with a purity of 99.996%.

After the leaching solution was controlled to pH 8 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.1 to the solution was added as a precipitant, and after leaching at a leaching temperature of 60 °C for 3 hours, washed, filtered, and dried to obtain cobalt, nickel, and manganese. Mixed products, the recovery rates of lithium, cobalt, nickel, and manganese are as high as 96%, 98%, 99%, and 90%, respectively. After adding HF to control the PH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled. The fluoride salt is obtained and the supernatant is recycled for the wet leaching process.

Example 6

Take 50g of decommissioned lithium-ion battery carbon residue from a domestic factory, the fixed carbon content is 86.18wt%, the volatile matter is 7.98wt%, and the ash content is 5.84wt%. Main element content of ash (wt%): Si 12.84, Ni 27.50, O 18.61, Mn 8.63, Co6.13, Al 5.96, Na 4.48, Fe 4.23, P 3.87, Zr 3.29, Cu 2.13. Crush the carbon slag to -150um (-100 mesh), and mechanically mix it with NH4F at a mass ratio of 1:0.7, then place the mixture in a corundum crucible, and keep it in a muffle furnace at 250°C for 3h in an argon atmosphere. After cooling, acid impurity removal was carried out on the obtained slag in sulfuric acid solution. The leaching temperature of sulfuric acid leaching was 70°C, leaching time was 2h, and liquid-solid ratio was 20:1. The acid leaching residue is washed with water until neutral, filtered, and the filter residue is dried, and tested according to the method for chemical analysis of graphite (GB/T-2008) to obtain ultrapure graphite powder with a purity of 99.995%.

After the leaching solution was controlled to pH 8 by introducing flue gas, ammonia carbonate with a molar ratio of 1:1.2 to the solution was added as a precipitant, and after leaching at a leaching temperature of 60 °C for 3 hours, washed, filtered, and dried to obtain cobalt, nickel, and manganese. Mixed products, the recovery rates of lithium, cobalt, nickel, and manganese are as high as 94%, 97%, 99%, and 90%, respectively. After adding HF to control the PH to 4, the waste water is cooled and crystallized, centrifuged, air-dried, and recycled. The fluoride salt is obtained and the supernatant is recycled for the wet leaching process.

It should be understood that these embodiments are only used to illustrate the present invention more clearly, rather than to limit the scope of the present invention. After reading the present invention, those skilled in the art will recognize various equivalent forms of the present invention. The modifications fall within the scope defined by the appended claims of this application.

Claims (10)

1. A resource treatment method of retired battery carbon slag, wherein the retired battery carbon slag mainly comprises C, Si, Ni, Co and Mn; the method is characterized by comprising the following steps:

s1, crushing and drying the carbon slag of the retired battery to be treated to obtain fine carbon slag;

s2, uniformly mixing the fine carbon residue obtained in the step S1 with fluorine salt to obtain a mixture;

wherein, the fluorine salt is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, aluminum fluoride and ammonium bifluoride;

s3, preserving the temperature of the mixture obtained in the step S2 for 0.5-4h under the conditions of protective atmosphere and 400 ℃ of 100-;

s4, leaching the slag obtained in the step S3 in water or an acidic aqueous solution, then carrying out solid-liquid separation, and washing a solid phase substance to obtain a leaching solution and graphite;

wherein the purity of the graphite is not less than 99.99%.

2. The recycling method according to claim 1, wherein in S1, the particle size of the fine carbon residue is less than 150 μm.

3. A resource treatment method according to claim 1, characterized in that in S2, the fine carbon residue and the villiaumite are uniformly mixed according to the mass ratio of 1:0.1-3 to obtain a mixture.

4. The method according to claim 1, wherein the fluorine salt is ammonium fluoride in S2.

5. The resource treatment method as claimed in claim 1, wherein in S3, the mixture is subjected to heat preservation for 2-4h under the conditions of protective atmosphere and 300 ℃ of 150 ℃ to obtain slag charge and flue gas.

6. The method according to claim 1, wherein the acidic aqueous solution contains HCl and HNO in S4₃、HF、H₂SO₄One or more of them.

7. The method according to claim 1, wherein the acid concentration in the acidic aqueous solution is 1 to 22 mol/L.

8. The resource treatment method according to claim 1, wherein in S4, the solid-liquid mass ratio is 1:5-30 during the leaching treatment;

the leaching temperature is 20-100 ℃, and the leaching time is 1-4 h.

9. A resource treatment method according to any one of claims 1 to 8, characterized in that the flue gas obtained in S3 is introduced into the leachate obtained in S4, and the pH of the leachate is controlled to 8 to 9; adding a precipitator into the leachate, and reacting at 30-100 ℃ for 0.5-3h to obtain waste liquid and metal precipitate;

wherein, the precipitant is one or more of ammonium carbonate, ammonium oxalate, oxalic acid and carbonic acid.

10. A resource treatment method according to claim 9, characterized in that the PH of the waste liquid is adjusted to 3 to 7, and then the waste liquid is sequentially cooled, crystallized, centrifugally separated and dried to obtain the fluorine salt.

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